434 research outputs found
A Multistate Friction Model for the Compensation of the Asymmetric Hysteresis in the Mechanical Response of Pneumatic Artificial Muscles
These days, biomimetic and compliant actuators have been made available to the main
applications of rehabilitation and assistive robotics. In this context, the interaction control of soft
robots, mechatronic surgical instruments and robotic prostheses can be improved through the
adoption of pneumatic artificial muscles (PAMs), a class of compliant actuators that exhibit some
similarities with the structure and function of biological muscles. Together with the advantage
of implementing adaptive compliance control laws, the nonlinear and hysteretic force/length
characteristics of PAMs pose some challenges in the design and implementation of tracking control
strategies. This paper presents a parsimonious and accurate model of the asymmetric hysteresis
observed in the force response of PAMs. The model has been validated through the experimental
identification of the mechanical response of a small-sized PAM where the asymmetric effects of
hysteresis are more evident. Both the experimental results and a comparison with other dynamic
friction models show that the proposed model could be useful to implement efficient compensation
strategies for the tracking control of soft robots
Topology optimization of 3D compliant actuators by a sequential element rejection and admission method
This work presents a sequential element rejection and admission (SERA) method for optimum topology design of three dimensional compliant actuators. The proposed procedure has been successfully applied to several topology optimization problems, but most investigations for compliant devices design have been focused on planar systems. This investigation aims to progress on this line, where a generalization of the method for three dimensional topology optimization is explored. The methodology described in this work is useful for the synthesis of high performance flexure based micro and nano manipulation applications demanding for both sensing and control of motion and force trajectories. In this case the goal of the topology optimization problem is to design an actuator that transfers work from the input point to the output port in a structurally efficient way. Here we will use the classical formulation where the displacement performed on a work piece modelled by a spring is maximized. The technique implemented works with two separate criteria for the rejection and admission of elements to efficiently achieve the optimum design and overcomes problems encountered by other evolutionary methods when dealing with compliant mechanisms design. The use of the algorithm is demonstrated through several numerical examples
Segmented Foot with Compliant Actuators and Its Applications to Lower-Limb Prostheses and Exoskeletons
Compliant actuators that mimic biological muscle performance with applications in a highly biomimetic robotic arm
This paper endeavours to bridge the existing gap in muscular actuator design
for ligament-skeletal-inspired robots, thereby fostering the evolution of these
robotic systems. We introduce two novel compliant actuators, namely the
Internal Torsion Spring Compliant Actuator (ICA) and the External Spring
Compliant Actuator (ECA), and present a comparative analysis against the
previously conceived Magnet Integrated Soft Actuator (MISA) through
computational and experimental results. These actuators, employing a
motor-tendon system, emulate biological muscle-like forms, enhancing artificial
muscle technology. A robotic arm application inspired by the skeletal ligament
system is presented. Experiments demonstrate satisfactory power in tasks like
lifting dumbbells (peak power: 36W), playing table tennis (end-effector speed:
3.2 m/s), and door opening, without compromising biomimetic aesthetics.
Compared to other linear stiffness serial elastic actuators (SEAs), ECA and ICA
exhibit high power-to-volume (361 x 10^3 W/m) and power-to-mass (111.6 W/kg)
ratios respectively, endorsing the biomimetic design's promise in robotic
development
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